Where is a good place to go to walk through what the possibilities are regarding that with LEDs, and what you need to have done? (It's a bit of a maze as to what is most easily retrofittable, and what adding LED cans requires of your electric wiring configuration.)

I'd like to read up in advance of asking an electrician to do this for us ... although even finding an electrician who's up on the latest in that fast-evolving LED field, at a decent cost, sounds like it might be a challenge.

One point I wasn't clear on after pawing through a lot of pages about recessed lights ... are there any *useful* LED options out there that actually just screw right into your existing incandescent recessed-light housings? Or that otherwise are easy for a homeowner to do w/regard to the recessed lights without technically (or per building code) needing to call an electrician?

There are screw in lights for 4 & 6 inch recessed cans. The most cost effective are cr6 lights sold under the ecostar home depot house brand.